The transient phenomena which appear when turning the power on or off for an inductive load such as a relay coil, raise important problems when the driving circuits are comprised of transistors. Indeed, the overvoltages caused by self-inductance effects and, more specifically, those caused when turning the power off, may entail the breakdown of the transistors included in the circuit. It can easily be understood that these problems are even more critical when the circuit elements are to be implemented in integrated circuit technology. The purpose of the subject invention, therefore, is to provide structures which avoid these phenomena which cause transistor breakdowns.
Many solutions have already been proposed to solve these problems, which are more or less complex and unreliable. In those solutions, one drawback is that only comparatively low power supplies (12 volts, for instance) can be used.